Light treatment system

ABSTRACT

The invention relates to a light treatment system. The light treatment system comprises a light source for emitting light for illuminating a part of a human or animal body for light treatment. The light treatment system further comprises a housing for emitting light towards the part of the human or animal body, and for at least partially covering the illuminated part of the human or animal body from view. The housing further comprises a window for emitting light from an inner part of the housing away from the housing.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application claims the benefit of priority of and describesrelationships between the following applications: wherein thisapplication is a continuation of U.S. patent application Ser. No.13/381,385, filed Mar. 16, 2012, issued as U.S. Pat. No. 9,415,237,which is a National Stage of International Application No.PCT/IB2010/052895, filed Jun. 24, 2010, which claims the priority offoreign application EP09164173.8 filed Jun. 30, 2009, all of which areincorporated herein in whole by reference.

FIELD OF THE INVENTION

The invention relates to a light treatment system.

BACKGROUND OF THE INVENTION

Light treatment systems are known per se. They are used, inter alia, inskin treatment systems for providing skin treatment for cosmetic andmedical applications. Medical light treatment, for example, compriseslight treatment using ultraviolet light radiation for treatment of, forexample, psoriasis and, for example, red or blue light treatment,combined with a photosensitizer, for the treatment of, for example,skin-cancer. Cosmetic light treatments, for example, comprise skinrejuvenation using, for example, a mixture of infrared light and amberlight. Such a skin rejuvenation process is, for example, described inthe U.S. Pat. No. 6,663,659.

Another system for skin treatment through illumination of light is knownfrom WO 2008/058713. In this skin treatment device for irradiating askin area, the skin treatment device has an elastic at least partiallyhollow ring structure for leak-proof placement of the skin treatmentdevice onto the skin. In another embodiment the skin treatment device,has a handle portion including a radiation source capable of emittingthe electromagnetic radiation and a detachably mounted attachment havingthe elastic at least partially hollow ring structure for the leak-proofplacement of the skin treatment device onto the skin.

A trend in such known light treatment devices is that they are designedto be battery operated such that an operator of the light treatmentdevice may freely use the light treatment device without being limitedin its use by a wire providing power or light to the light treatmentdevice. For battery operated equipment, the power required by theequipment is typically always too high.

SUMMARY OF THE INVENTION

So it is an object of the invention to provide a light treatment devicewhich has reduced power usage.

According to a first aspect of the invention the object is achieved witha light treatment system as claimed in claim 1.

The light treatment system according to the first aspect of theinvention comprises a light source for emitting light for illuminating apart of a human or animal body for light treatment, the light treatmentsystem comprising a housing for emitting light towards the part of thehuman or animal body, and for at least partially covering theilluminated part of the human or animal body from view, the housingcomprising a window for emitting light from an inner part of the housingaway from the housing.

A rim between the housing and the human or animal body via which lightmay leak away from the housing is not considered to be a window forallowing light from the inner part of the housing to be emitted awayfrom the housing, because such a rim between the housing and the humanor animal body is not part of the housing. Such uncontrolled leakage oflight is usually undesirable and is preferably to be avoided as theintensity of the leaked light is difficult to control which might bedangerous to people working with the light treatment system and whichmay be annoying for people working with the light treatment system.Furthermore, the wavelength of the light for illuminating the part ofthe human or animal body may be harmful to humans and as such leakage oflight from the rim between the human or animal body and the housing ofthe light treatment system is to be avoided.

Light emitted by the light source for light treatment may comprise lightvisible to the naked human eye and/or may comprise light invisible tothe naked human eye, such as infrared light and/or ultraviolet light.The light source may also be configured for emitting light having arelatively broad emission spectrum which may comprise a substantiallycontinuous spectrum over a predefined range or which may comprise adiscontinuous spectrum over the predefined range. Such a discontinuousspectrum may comprise a plurality of emission peaks of individual lightemitters inside the light source. Such individual light emitters may,for example, emit light around a central wavelength having a relativelynarrow spectral peak. Light emitters emitting a relatively narrowspectral peak, for example, comprise semiconductor light emitters suchas light emitting diodes, laser diode and/or organic light emittingdiodes. Light emitters emitting a relatively broad and substantiallycontinuous spectrum may comprise all types of lamps emitting arelatively broad spectrum. The emission spectrum of a light emitter may,for example, be enhanced via the use of luminescent materials.

An effect of the light treatment system according to the invention isthat the window in the housing may be used as indicator whether thelight treatment system is operating and/or functioning well. The use ofthe window as indicator for the operation or functioning of the lighttreatment system has a benefit in that no additional light source and/orelectronic circuitry is required for indicating whether the lighttreatment system is operating. Especially when using battery-operatedlight treatment systems, the power requirements of the light treatmentsystem as a whole determine the operational time between battery-chargesduring which the light treatment system may operate. An additional lightsource and/or electronic circuitry would then reduce the operationaltime between battery-charges which would not be preferred.

A further benefit of the light treatment system according to theinvention is that it is more cost effective, because the additional costof the additional light source and/or electronic circuitry is notrequired. As the light treatment system may be a consumer system whichconsumers may use, for example, at home for light treatment, the cost ofthe light treatment system is an important competitive advantage.Furthermore, the high number of light treatment systems which may berequired for a consumer market may make an even marginal cost reductionbeneficial to the producer of the light treatment system.

In an embodiment of the light treatments system, the light emitted viathe window comprises light of a different wavelength compared to thelight emitted by the light treatments system towards the part of thehuman or animal body. This may, for example, result from lightconversion means being present inside the housing to convert at least apart of the light emitted towards the human or animal body into light ofa different wavelength.

So, in an embodiment of the light treatments system, light conversionmeans are present inside the housing, the light conversion means beingconfigured for converting light impinging on the conversion means intolight of a longer wavelength. The light conversion means may be part ofthe light treatment in which, for example, an ointment, salve or creammay be applied to the part of the human or animal body, for example, toimprove the absorption of the light emitted by the light treatmentsystem and/or to generate a light-enhanced or light-initiated chemicalreaction which is required or beneficial for the light treatmenttherapy. In such ointment, salve or cream, the light conversion meansmay be present or added to convert a part of the light emitted by thelight treatment system and impinging on the ointment, salve or cream tobe converted into light having the different wavelength. Alternatively,the light conversion means may be applied to a wall of the housing ofthe light treatment system.

In an embodiment of the light treatments system, the window comprisesthe light conversion means for converting light impinging on theluminescent material into light of a longer wavelength. When using thewindow in the housing as indicator to provide information about theworking of the light treatment system, such indicator often is requiredto emit light of a specific color, for example, the color red. Skintreatment may be done using light of a completely different color, forexample, using substantially blue light or even radiation not visible tothe human eye. A simple filtering of the light to only transmit therequired component of the light may not work because the light used forthe treatment may not comprise the required color component. In such asituation, a thin layer of luminescent material on the window orimplemented inside the window may be sufficient to convert light usedfor the light treatment on the part of the human or animal body intolight of a longer wavelength, for example, into red light. As such, ared indicator window is generated which emits red light when the lighttreatment system is in operation by converting at least a part of thelight which is emitted towards the part of the human or animal body andwhich impinges on the window, into light of the longer wavelength, forexample, light of the color red. Of course any color may be used toprovide the user with information about the working of the lighttreatment system.

In an embodiment of the light treatments system, the light conversionmeans are configured for absorbing ultraviolet light and for convertinga part of the absorbed ultraviolet light into visible light. Especiallywhen using light which is invisible to the naked human eye, a simplewindow in the housing will not be sufficient to indicate that the lighttreatment system is working properly. Luminescent material as indicatedin the previous part may be required. For some skin treatments,ultraviolet light is used, and for others infrared light is used. Suchultraviolet or infrared light may be harmful to the human eye and assuch the housing of the light treatment system may be used to shield theharmful light from the human eye. Still, there should be a low-cost wayto provide the user with information whether or not the light treatmentsystem is working properly. An indicator light may be used which howeveradds to the cost of the light treatment system or which may reduce theoperational lifetime between battery-charges of a battery-operatedsystem, as indicated previously. Typically a part of the light emittedby the light treatment system toward the part of the human or animalbody will reflect from the human or animal body back into the housing.This reflected light may be indicated as stray light and only marginallycontributes to the treatment effect. Some of this reflected light may,for example, impinge on the window comprising the luminescent materialand the luminescent material of the window may convert some of theimpinging ultraviolet light into visible light used to indicate theoperation of the light treatment system.

A further benefit of this conversion of the ultraviolet light intovisible light is that the operation and/or functioning of the lighttreatment system can be inspected relatively safely, as the luminescentmaterial converts the part of the ultraviolet light into visible lightwhich is safe to the human or animal eye. In addition, the windowthrough which the converted light is visible from outside the housingdoes not need to be manufactured of specific material to transmitultraviolet radiation. In a preferred embodiment of the light treatmentsystem the luminescent material is applied to a wall of the windowfacing toward the part of the human or animal body, or said differently,facing the inner part of the housing. In such an arrangement, theultraviolet light is converted into visible light before the lighttransits the window in the light treatment system. Because materialswhich are transmissive for ultraviolet typically are relativelyexpensive, the use of the luminescent material for convertingultraviolet light into visible light omits the need for the ultraviolettransmissive materials and as such reduces the cost of the lighttreatment system.

In an embodiment of the light treatments system, the light treatmentsystem comprises a control circuit being configured for controlling thelight source for emitting the light towards the part of the human oranimal body in a pulsed mode operation comprising a dead-time duringwhich no light is emitted by the light treatment system towards the partof the human or animal body. For most light treatment sequences, apulsed mode of operation of the light emitted toward the part of thehuman or animal body is required. As different treatment sequences mayrequire a different frequency and/or a different dead-time, the lighttreatment system according to the invention comprises the controlcircuit.

In an embodiment of the light treatments system, the control circuit isconfigured for controlling a frequency and/or dead-time of the pulsedmode operation, the frequency and/or dead-time being selected for beingperceived by a naked human eye as a substantially continuousillumination of the part of the human or animal body while stillproviding an effective light treatment. Using, for example, a frequencyabove, for example, 50 Hertz, the flashing of the light source isperceived as a substantial continuous light source by the human eye.Flashing light sources may be perceived relatively annoying. Especiallywhen having to work with such flashing light sources for a considerabletime the flashing light may even cause health problems to the peopleusing them, such as headache or dizziness or even epileptic attacks. Forlight treatment systems the dead-time may be more important to obtain aneffective light treatment compared to the overall frequency of thepulsed mode operation. As such, the control circuit may be configured tocontrol the frequency and/or dead-time of the pulsed mode operation suchthat the light emitted by the window is perceived by the human eye ascontinuous light while still providing an effective light treatment. Assuch, working conditions for people operating the light treatment systemmay be improved substantially and problems such as headache, dizzinessor epileptic attacks may be avoided.

In an embodiment of the light treatments system, the window comprises afurther light source controlled by the control circuit for emittinglight during at least a part of the dead-time during which no light isemitted by the light treatment system towards the part of the human oranimal body. Such use of the further light source may provide similarbeneficial effects in relation to the working conditions for the peopleoperating the light treatment systems as mentioned above. Because thefurther light source is switched on during at least a part of thedead-time during which no light is emitted by the light treatment systemtowards the part of the human or animal body, this additional light fromthe further light source may cause the light emitted from the window tobe perceived as a substantial continuous emission of light, thusreducing any negative effects resulting from flashing lights, thusimproving the working conditions of the people operating the lighttreatment systems.

In an embodiment of the light treatments system, the light treatmentsystem comprises the light conversion means comprising luminescentmaterial, wherein the luminescent material comprises a decay time beingconfigured for reducing the dead-time of the light treatment system forgenerating a light emission from the window being perceived by the nakedhuman eye as a continuous light emission. The decay time of theluminescent material may, for example, be longer than the dead-time togenerate a substantial continuous emission of light from the window.Alternatively, the decay time may be chosen such that the remainingdead-time is too short to be noticed by the naked human eye such thatthe emission from the window is perceived as being continuous by thenaked human eye. The use of the luminescent material having a decay timeconfigured for reducing the dead-time to generate a perceived continuouslight emission results in a further alternative manner to cause thelight emitted by the window to be perceived as continuous light emittedfrom the window of the light treatment system. When the decay time islonger than the dead-time, the luminescent material will continue toemit light while the light source of the light treatment system is notemitting light towards the part of the human or animal body. There maybe some residual intensity variations visible via the window.

In an embodiment of the light treatments system, the housing comprisesresilient material for contacting the human or animal body. Contactbetween the human or animal body and the housing via the resilientmaterial is typically more pleasant to the humans or animals having toundergo the light treatment.

In an embodiment of the light treatments system, the resilient materialis configured for contacting the human or animal body for preventinglight to leak away from the housing. Especially when using ultravioletlight for the light treatment, the leakage of ultraviolet light shouldbe avoided, both to protect the eyes of the person operating the lighttreatment system and to reduce the exposure to ultraviolet light to theperson operating the light treatment system and to the remainder of thehuman or animal body which does not require the treatment. When, forexample, the light treatment system is used for the treatment ofpsoriasis or vitiligo, relatively harmful ultraviolet radiation is used.This radiation may be harmful to the remainder of the body and exposureto that specific ultraviolet light should be avoided. Using theresilient material according to the current embodiment ensures that thepossible harmful ultraviolet radiation does not leak away from thehousing.

In an embodiment of the light treatments system, the window is arrangedin the resilient material. The intensity of the stray light near thepart of the human or animal body which is to be illuminated isrelatively high, thus allowing good visibility of the stray lightemitted via the window in the resilient material. Furthermore, as thewindow is arranged in the resilient material, part of the window mayalso be resilient allowing a user to manipulate the dimensions of thewindow by manipulating the amount of force with which the lighttreatment system is applied to the human or animal body. If, forexample, the intensity of the light emitted from the window isrelatively high, the dimensions of the window may be reduced byincreasing the force with which the light treatment system is applied,thus reducing the intensity of the light emitted from the window.

In an embodiment of the light treatments system, the light sourcecomprises a first light emitter and a second light emitter, the firstlight emitter emitting light comprising a different spectrum compared tothe second light emitter. Typically light comprising a mixture ofdifferent wavelengths is required to obtain an effective lighttreatment. Well known mixtures for, for example, skin rejuvenation is bymixing infra-red light with amber light which is emitted toward the partof the human or animal body at a predefined frequency and/or dead-time.Instead of applying a single light source which emits a spectrumcomprising the required wavelength peaks in its spectrum, the lightsource preferably comprises a plurality of light emitters in which eachof the light emitters contributes part of the spectrum of the lightrequired for the treatment. Especially the use of light emitting diodesor other solid-state light emitters such as laser diodes, organic lightemitting diode may beneficially be used, to generate the requiredspectrum of light for the light treatment may be preferred as suchsolid-state light emitters typically have a relatively high efficiencyand as such may be very beneficial when the light treatment system isbattery-operated.

In an embodiment of the light treatments system, the control circuit forcontrolling the light source for emitting the light towards the part ofthe human or animal body in a pulsed mode operation, wherein the controlcircuit is configured for controlling the first light emitter to emitlight at a first pulsed mode of operation and for controlling the secondlight emitter to emit light at a second pulsed mode of operation beingdifferent from the first pulsed mode of operation. Such a controlcircuit may allow the spectrum of the light applied via the lighttreatment system to vary in time which allows maximum flexibility inapplying the light treatment.

In an embodiment of the light treatments system, the first light emitteremits ultraviolet light and the second light emitter emits visiblelight. The combination of ultraviolet light and visible light may bebeneficial for, for example, preparing the skin to the ultraviolet lighttreatment, or, for example, for relieving the skin with visible lightafter a treatment with ultraviolet light.

In an embodiment of the light treatments system, the first light emitteremits ultraviolet light and the second light emitter emits infraredlight. The combination of ultraviolet light and infrared light may bebeneficial for locally increasing the temperature to, for example,improve the blood flow, and for relieving the pain before, during orafter the treatment with ultraviolet light.

In an embodiment of the light treatments system, the first light emitteremits visible light and the second light emitter emits infrared light.The combination of visible light and infrared light may be beneficialfor locally increasing the temperature and improve blood flow.

In an embodiment of the light treatments system, the first light emitteremits ultraviolet light comprising light of a first wavelength and thesecond light emitter emits ultraviolet light comprising light of asecond wavelength. The combination of ultraviolet light comprising lightof the first wavelength and the second wavelength may be beneficial whena broader range of ultraviolet light is needed than a single lightemitter may be able to provide.

In an embodiment of the light treatments system, the first light emitteremits visible light and the second light emitter emits visible light.Especially in the treatment of skin-cancer different photosensitizersmay be used which require different wavelengths of visible light.

In an embodiment of the light treatments system, the light treatmentsystem comprises massage means for massaging the part of the human oranimal body. A benefit of the adding of massage means is that the bloodcirculation at the part of the human or animal body is improved whichfurther improves the effectiveness of the light treatment. A furtherbenefit is that the massage means may provide relaxation to the human oranimal body making the light treatment more pleasant to the human oranimal undergoing the treatment.

In an embodiment of the light treatments system, the light treatmentsystem comprises dispensing means for dispensing a substance to the partof the human or animal body. The substance may be an ointment, balm,salve and/or cream to aid the light treatment or to make the lighttreatment more pleasant. For example, the substance may be a cooling gelwhich keeps the skin temperature below 38 degrees. Alternatively, thesubstance may comprise a luminescent material for indicating which partshave already been treated with the light treatment system and forconverting part of the light generated by the light treatment system tobe visible through the window. Further alternatively, the substance maycomprise a photo catalytic cleaning ointment which removes dead skincells using, for example, deep blue light. Such removal of dead skincells may improve the penetration depth of the light emitted by thelight treatment system towards the part of the human or animal body.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter.

In the drawings:

FIG. 1 shows a schematic cross-sectional view of a first embodiment ofthe light treatment system according to the invention,

FIG. 2 shows a schematic cross-sectional view of a second embodiment ofthe light treatment system according to the invention, and

FIGS. 3A and 3B show schematic detailed sections of the secondembodiment of the light treatment system having different windows.

The figures are purely diagrammatic and not drawn to scale. Particularlyfor clarity, some dimensions are exaggerated strongly. Similarcomponents in the figures are denoted by the same reference numerals asmuch as possible.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a schematic cross-sectional view of a first embodiment ofthe light treatment system 10 according to the invention. The lighttreatment system 10 comprises a housing 40 comprising a light source 20.In the embodiment shown in FIG. 1, the light source 20 comprises aplurality of light emitters 20A, 20B, 20C and, optionally, a lightmixing chamber 26 for mixing the light emitted by the plurality of lightemitters 20A, 20B, 20C. The inner wall of the housing 40 indicated withthe arrows and reference number 27 preferably comprises a reflectivesurface for reflecting light towards the part of the human or animalbody 30 which is to be treated in operation. Optionally, the lightmixing chamber 26 may comprise a light emission window 24 which may be adiffusing window 24 for further mixing the light emitted from the lightemission window 24 towards the part of the human or animal body 30 whichis to be treated by the light treatments system 10. Alternatively, thelight emission window 24 may not diffuse the light which is transmittedbut may transmit the light substantially unhindered. In such a case thelight emission window 24 may be configured for protecting the lightemitters 20A, 20B, 20C from dirt and dust and/or from ointments, salvesor creams which may be used during the light treatment.

In FIG. 1, the light emitted toward the part of the human or animal body30 is indicated with dashed arrows 100 pointing towards the part of thehuman or animal body 30 which is to be treated by the light treatmentsystem 10. The interface between the housing 40 and the part of thehuman or animal body 30 is provided with resilient material 80 whichensures a pleasant interface between the light treatment system 10 andthe human or animal body. The resilient material 80 may also be used toensure that no light leaks away from the housing 40 in an uncontrolledmanner. Some of the light used for light treatment may be harmful. Suchlight may be damaging to the skin and/or eyes of the humans or animalsundergoing the light treatment and/or to people assisting or providingthe light treatment. As such, by using a resilient material 80 asinterface between the housing 40 and the human or animal body, theleakage of light may be prevented.

In the housing 40 a window 50 is present for emitting light from aninner part of the housing 40 away from the housing 40. The window 50 inthe housing 40 is used as an indicator 50 to indicate whether the lighttreatment system is operating and/or functioning well. As such, noadditional light source and/or electronic circuitry is required forindicating whether the light treatment system is operating whichtypically reduces the overall power requirements of the light treatmentsystem 10. A further benefit of the use of the window 50 is that thecost may be reduced as no additional light source and/or electroniccircuitry is required. Because the light treatment system may be solddirectly to consumers, an even marginal cost reduction is beneficial tothe producer of the light treatment system.

The light treatment system 10 according to the invention may alsocomprise a control circuit 70 for controlling the light source 20. Thecontrol circuit 70 may, for example, control the light source 20 to emitthe light towards the part of the human or animal body 30 in a pulsedmode operation. The time during which no light is emitted is indicatedas dead-time. Most light treatment sequences require a pulsed mode ofoperation for the light treatment to be efficient. Because differenttreatment sequences may require a different frequency and/or a differentdead-time, the light treatment system 10 according to the inventioncomprises the control circuit 70. The control circuit 70 may also beconfigured to control the different light emitters 20A, 20B, 20C of thelight source 20. The controlling of the different light emitters 20A,20B, 20C also include the situation in which the controller 70 operatesthe different light emitters 20A, 20B, 20C at different frequencies andat different dead-times. As such, different contributions of the lightemitters 20A, 20B, 20C may be varied at will and/or as required toobtain an efficient light treatment.

A further benefit when being able to control the frequency and/ordead-time of the light source 20, and even to control the individuallight emitters 20A, 20B, 20C is that a specific pulsed mode of operationmay be selected such that the operation of the light source 20 in thelight treatment system 10 may be perceived by the naked human eye as asubstantially continuous illumination. Using, for example, a frequencyabove, for example, 50 Hertz, the flashing of the light source 20 isperceived as a substantial continuous light source 20 by the human eye.Because flashing light sources 20 may be perceived as annoying and mayeven cause health problems, the controlling of the frequency and/ordead-time to obtain an efficient light treatment while operating in aperceived continuous mode may be beneficial.

The light source may, for example, comprise a first light emitter 20Aemitting amber light, a second light emitter 20B emitting infrared lightand a third light emitter 20C emitting amber light. Such a configurationof light emitters 20A, 20B, 20C may beneficially be used for lighttreatment for skin rejuvenation. Alternatively other combinations oflight emitters 20A, 20B, 20C may be used such that the light treatmentsystem 10 may be used for the treatment of psoriasis, acne, vitiligo andskin cancer.

The light treatments system 10 according to the invention may alsocomprise massage means (not shown) for massaging the part of the humanor animal body 30. Such massage means may improve the blood circulationand provide relaxation to the human or animal undergoing the treatment.The light treatment system 10 may also comprise dispensing means (notshown) for dispensing a substance to the part of the human or animalbody 30. The substance may be an ointment, balm, salve and/or cream toaid the light treatment or to make the light treatment more pleasant.Such substance may be a cooling gel to keep the skin temperature below38 degrees. The substance may also comprise a photo catalytic cleaningointment which removes dead skin cells using, for example, deep bluelight. Such removal of dead skin cells may improve the penetration depthof the light emitted by the light treatment system 10 towards the partof the human or animal body 30.

FIG. 2 shows a schematic cross-sectional view of a second embodiment ofthe light treatment system 12 according to the invention. In the currentembodiment the light source 22 is constituted of two light emitters 22A,22B which emit light into a light guide 28. The light emitted by thelight emitters 22A, 22B is mixed inside the light guide 28 before thelight is emitted from the light guide 28 via light extraction means (notshown) toward the part of the human or animal body 30—again indicatedwith the dashed arrows having reference number 100. This secondembodiment of the light treatments system 12 also comprises a housing 42being connected to the human or animal body via the resilient material80. Also a control circuit 70 is present for controlling the lightsource 22 and/or for controlling the individual light emitters 22A, 22Bof the light source 22.

The embodiment of the light treatment system 12 as shown in FIG. 2 alsocomprises a window 52 for emitting light from an inner part of thehousing 42 away from the housing 42. The window 52 as shown in FIG. 2also comprises luminescent material 60 for converting at least a part ofthe impinging light from the light source 22 into light of a longerwavelength of which subsequently a part is transmitted through thewindow 52. The luminescent material 60 may be applied as a layer on asurface of the window 52. Alternatively, the luminescent material 60 maybe mixed in the material of the window 52 (not shown) and as such,luminescent particles may be distributed throughout the window 52.

The luminescent material 60 of the window 52 may, for example, beconfigured for converting light impinging on the luminescent material 60into light of a longer wavelength. When using the window 52 in thehousing 42 as indicator to provide information about the working of thelight treatment system 12, such indicator often is required to emitlight of a specific color, for example, the color red. Choosing aspecific luminescent material 60, part of the light emitted by the lightsource 20 may be converted into the right color to enable a redappearance of the window 52 when the light treatment system 12 isoperating. Alternatively, the skin treatment may be done using light ofa completely different color, for example, using substantially bluelight or even light not visible to the human eye. A simple filtering ofthe light to only transmit the required component of the light may notwork because the light used for the treatment may not comprise therequired color component. In such a situation, a thin layer ofluminescent material 60 on the window 52 or distributed inside thewindow 52 may be sufficient to convert light used for the lighttreatment on the part of the human or animal body 30 into light of alonger wavelength which may be visible and as such may be used asindicator for indicating whether the light treatment system 12 isworking.

The luminescent material 60 may also be configured for absorbingultraviolet light and for converting a part of the absorbed ultravioletlight into visible light. For some skin treatments, ultraviolet light isused. Such ultraviolet light may be harmful to the human eye and as suchthe housing 42 of the light treatment system 12 may be used to shieldthe harmful light from the human eye. Still, there should be a low-costway to provide the user with information whether or not the lighttreatment system 12 is working properly. Using luminescent material 60at or in the window 52 may convert some of the impinging ultravioletlight into visible light used to indicate the operation of the lighttreatment system 12.

In an alternative embodiment of the light treatment system 12 theluminescent material 60 comprises a decay time which is configured forreducing the dead-time of the light treatment system 10. This reducingof the dead-time may cause the light emitted at a specific frequency andhaving a specific dead-time to be perceived by the naked human eye as asubstantial continuous light emission. The decay time of the luminescentmaterial may, for example, be longer than the dead-time to generate asubstantial continuous emission of light from the window. Alternatively,the decay time may be chosen such that the remaining dead-time is tooshort to be noticed by the naked human eye such that the emission fromthe window is perceived as being continuous by the naked human eye.

In an alternative embodiment, other light conversion means may bepresent inside the housing 52. In such an embodiment, the lightconversion means may be part of the light treatment in which, forexample, an ointment, salve or cream may be applied manually or via thedispensing means (not shown) to the part of the human or animal body 30,for example, to improve the absorption of the light emitted by the lighttreatment system 12 and/or the generate a light-enhanced orlight-initiated chemical reaction which is required or beneficial forthe light treatment therapy. Alternatively, the light conversion means62 (see FIG. 3B) may be applied to a wall of the housing 42 of the lighttreatment system 12. Such an embodiment may be beneficial when usingnon-visible light for the light treatment of which a part of thenon-visible light is converted by the light conversion means 62 intovisible light of which a part is emitted via the window 56. Of course,applying the light conversion means 62 on the window 56 would result ina most efficient conversion requiring as little as possible lightconversion means 62 as half of the light generated by the lightconversion means 62 is emitted by the window 56.

FIGS. 3A and 3B show schematic detailed sections of the secondembodiment of the light treatment system 12 having different windows 54,56. In the first detailed section, shown in FIG. 3A, the window 54comprises a further light source 58 controlled by the control circuit70. The further light source 58 may be controlled to emit light duringat least a part of the dead-time. Such use of the further light source58 provides similar beneficial effects in relation to the workingconditions for the people operating the light treatment systems asmentioned above. Because the further light source 58 may be switched onduring at least a part of the dead-time during which no light is emittedby the light treatment system 12 towards the part of the human or animalbody 30, this additional light from the further light source 58 maycause the light emitted from the window 54 to be perceived as asubstantial continuous emission of light.

In the embodiment shown in FIG. 3B the window 56 is arranged in theresilient material 80. Such an arrangement would allow a user tomanipulate the dimensions of the window 56 by manipulating the amount offorce with which the light treatment system 12 is applied to the humanor animal body 30 and as such manipulate the amount of light transmittedthrough the window 56. In an alternative embodiment light conversionmeans 62 may be applied to the inner wall of the housing 42 of the lighttreatment system 12 for converting part of the light generated insidethe light treatment system 12 into light of a different wavelength whichmay be visible through the window 56.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. Use of the verb “comprise” and itsconjugations does not exclude the presence of elements or steps otherthan those stated in a claim. The article “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention may be implemented by means of hardware comprising severaldistinct elements. In the device claim enumerating several means,several of these means may be embodied by one and the same item ofhardware. The mere fact that certain measures are recited in mutuallydifferent dependent claims does not indicate that a combination of thesemeasures cannot be used to advantage.

The invention claimed is:
 1. A light treatment system comprising: an ultraviolet treatment light source configured to emit an ultraviolet treatment light of a treatment wavelength directed towards a part of a human or animal body for light treatment, configured to directly irradiate said part of said human or animal body, a housing configured to cover the treatment light source from exterior view and configured to at least partially cover the illuminated part of the human or animal body from external view, an indication window of the housing configured to allow the emission of an indication light of an indication wavelength from an inner part of the housing away from the housing in a direction different from the direction towards the part of the human or animal body of the treatment light, wherein the indication light emitted by the indication window is sourced from the treatment light source and comprises transformed light of a different wavelength than the treatment wavelength of the treatment light emitted by the light source directed towards the part of the human or animal body for treatment thereof.
 2. The system of claim 1, wherein the difference between the indication wavelength and the treatment wavelength comprises the indication wavelength is longer than the treatment wavelength.
 3. The system of claim 1, comprising a light converter within the housing, configured to convert at least a part of the treatment light of the treatment wavelength impinging on the light converter into the transformed indication light of the different indication wavelength.
 4. The system of claim 3, wherein the light converter comprising luminescent material within the indication window, the luminescent material converting the treatment light impinging on the luminescent material into indication light of a longer wavelength.
 5. The system of claim 4, wherein the light converter is configured to absorb ultraviolet light and to convert a part of the absorbed ultraviolet light into visible light.
 6. The system of claim 1, comprising a control circuit configured to control the treatment light source to emit the treatment light towards the part of the human or animal body in a pulsed mode operation comprising a dead-time during which no treatment light is emitted by the treatment light source towards the part of the human or animal body.
 7. The system of claim 6, wherein the control circuit is configured to control a frequency and/or dead-time of the pulsed mode operation, the frequency and/or dead-time being selected to be perceived by a naked human eye as a substantially continuous illumination of the part of the human or animal body while still providing an effective light treatment.
 8. The system of claim 6, wherein the window comprises a further light source controlled by the control circuit for emitting light during at least a part of the dead-time during which no treatment light is emitted by the treatment light source towards the part of the human or animal body.
 9. The system of claim 6 comprising a light converter comprising luminescent material within the indication window, the luminescent material converting the treatment light impinging on the luminescent material into indication light of a longer wavelength, the luminescent material being pre-selected to have a sufficient decay time so that the dead time of the Treatment light emission resulting in dead-time of the indication light emission from the window is perceived by the naked human eye as a continuous light emission.
 10. The system of claim 1, wherein the housing comprises resilient material for contacting the human or animal body and preventing light from leaking between the housing and the human or animal body.
 11. The system of claim 10, wherein the window for indication light emission is arranged in the resilient material.
 12. The system of claim 1, wherein the treatment light source comprises a first light emitter and a second light emitter, the first light emitter emitting light comprising a different spectrum from the spectrum of light emitted from the second light emitter.
 13. The system of claim 12 comprising a control circuit for controlling the treatment light source for emitting the light towards the part of the human or animal body in a pulsed mode operation, wherein the control circuit is configured for controlling the first light emitter to emit light at a first pulsed mode of operation and for controlling the second light emitter to emit light at a second pulsed mode of operation being different from the first pulsed mode of operation.
 14. The system of claim 12, wherein: the first light emitter emits ultraviolet light and the second light emitter emits visible light, or the first light emitter emits ultraviolet light and the second light emitter emits infrared light, or the first light emitter emits visible light and the second light emitter emits infrared light, or the first light emitter emits ultraviolet light comprising light of a first wavelength and the second light emitter emits ultraviolet light comprising light of a second wavelength, or the first light emitter emits visible light and the second light emitter emits visible light.
 15. The system of claim 1, comprising: a massager to message the part of the human or animal body covered by the housing.
 16. The system of claim 1, comprising: a substance dispenser to dispense a substance onto the part of the human or animal body covered by the housing.
 17. A method of operating a light treatment system, comprising: covering a part of a human or animal body with a housing to at least partially prevent external view of the covered part of the human or animal part; emitting ultraviolet treatment light from an ultraviolet treatment light source covered by the housing, the ultraviolet treatment light source having a treatment wavelength and being directed towards the part of a human or animal body covered by the housing, to provide a light treatment to the part of the human or animal, irradiating said part of said human body or animal body with the ultraviolet treatment light emitted from the ultraviolet treatment light source, emitting an indication light sourced from the emitting treatment light via an inner part of the housing and passing from the inner part of the housing through an indication window in the housing, the indication light having an indication wavelength and being in a direction different from the direction towards the part of the human or animal body of the treatment light, wherein the indication light emitted by the indication window comprises essentially light of a different wavelength than the treatment wavelength of the treatment light emitted by the light source directed towards the part of the human or animal body for treatment thereof.
 18. A control circuit that is not a transitory propagating signal or wave, the circuit comprising control information for controlling a method of operating a light treatment system, comprising: covering a part of a human or animal body with a housing to at least partially prevent external view of the covered part of the human or animal part; emitting treatment light from an ultraviolet treatment light source covered by the housing, the ultraviolet treatment light source having a treatment wavelength and being directed towards the part of a human or animal body covered by the housing, to provide a light treatment to the part of the human or animal, irradiating said part of said human body or animal body with the treatment light emitted from the ultraviolet treatment light source, emitting an indication light sourced from the emitting treatment light via an inner part of the housing and passing from the inner part of the housing through an indication window in the housing, the indication light having an indication wavelength and being in a direction different from the direction towards the part of the human or animal body of the treatment light, wherein the indication light emitted by the indication window comprises essentially light of a different wavelength than the treatment wavelength of the treatment light emitted by the light source directed towards the part of the human or animal body for treatment thereof. 